Fault interrupting devices are designed to trip in response to the detection of a fault condition at an AC load. The fault condition can result when a person comes into contact with the line side of the AC load and an earth ground, a situation which can result in serious injury. A ground fault circuit interrupter (GFCI) detects this condition by using a sense transformer to detect an imbalance between the currents flowing in the line and neutral conductors of the AC supply, as will occur when some of the current on the line side is being diverted to ground. When such an imbalance is detected, a relay or circuit breaker within the GFCI device is immediately tripped to an open condition, thereby removing all power from the load.
Many types of GFCI devices are capable of being tripped not only by contact between the line side of the AC load and ground, but also by a connection between the neutral side of the AC load and ground. The latter type of connection, which may result from a defective load or from improper wiring, is potentially dangerous because it can prevent a conventional GFCI device from tripping at the required threshold level of differential current when a line-to-ground fault occurs.
A ground fault is not the only class of potentially dangerous abnormal operating conditions. Another type of undesirable operating condition occurs when an electrical spark jumps between two conductors or from one conductor to ground, which is also known as an arcing path. This spark represents an electrical discharge through the air and is objectionable because heat is produced as an unintentional by-product of the arcing. Such arcing faults are a leading cause of electrical fires.
Arcing faults can occur in the same places that ground faults occur; in fact, a ground fault would be called an arcing fault if it resulted in an electrical discharge, or spark, across an air gap. A device known as an arc fault circuit interrupter (AFCI) can prevent many classes of arcing faults. Both GFCIs and AFCIs are referred to as fault protection devices.
Solenoid assemblies in existing fault protection devices use a solenoid to drive an armature against a plunger to release a latch. The armature abuts the plunger such that the solenoid must drive both the armature and the plunger toward the latch. Thus, when the solenoid is activated, a large amount of activating force is required to drive both the armature and the plunger toward the latch. Furthermore, the activating force must overcome frictional forces.
Thus, there is a continuing need to provide an improved impact solenoid assembly for an electrical receptacle.